A deodorizing system such as shown in FIG. 5 has been conventionally adopted in a process for removing gas (referred to as odor gas) including odor components generated in a foaming oven or a hot-air drier such as a paint drying oven. The deodorizing system comprises: a hot blast stove 102 for supplying hot air having a medium/low temperature; a thermal equipment 101 such as a hot-air drier or a foaming oven for utilizing hot air supplied from the hot blast stove 102 to effect predetermined drying or foaming process on a work W; and a deodorizing furnace 103 which takes out and burn or heat-decomposes the odor gas generated in the thermal equipment 101 for deodorization. Here, hot air having a medium/low temperature, e.g., approximately 300.degree. C. required in the thermal equipment 101 is generated in the hot blast stove 102, and atmosphere gas or flames having a high temperature, e.g., approximately 1000.degree. C. required for burning or heat-decomposing the odor gas components is formed in the deodorizing furnace 103.
The odor gas generated in a paint drying oven or a foaming oven, however, includes a large quantity of mist before deodorization and this mist is high-temperature gas including a large amount of carbonized dust after deodorization, whereby heat recovery becomes difficult. Even though a heat exchanger is used to carry out heat recovery, the heat exchanger may soon be out of service and the heat efficiency is low. Thus, the high-temperature gas generated in the deodorizing furnace is not subjected to the effective heat utilization and it is directly exhausted. A difference in temperature between the heat required in the thermal equipment and the heat required for deodorization is not less than approximately 700.degree. C., and hence a common heat source can not be used. Two different heat sources must be prepared for the hot blast stove and the deodorizing furnace, thereby taking a large space and increasing the facility cost.